I am looking to set up a 75 gallon tank for my crested geckos but not sure what type of subtarate is safe? I have many plants that are safe for them. Just not sure what I can use to help the plants grow, make it look natural and not hurt me geckos.

also would like to know if there is any other animal that can live with them safely.

Any and All info will be greatly appriciated.
Thanks